| Lattice structures are widely used in aerospace,transportation,and other engineering fields due to their high specific strength,high specific stiffness,and good energy absorption capacity.Therefore,designing lattice structures with better mechanical properties becomes particularly important.In this thesis,using the metal multiphase strengthening mechanism,a dual phase lattice structure was designed to improve the mechanical properties and energy absorption ability of the lattice structure.The lattice structure was prepared by SLM technology,and the mechanical properties,energy absorption ability,and deformation behavior of the lattice structure were studied through experiments and numerical simulation.The main research contents are as follows:(1)Using BCCZ crystal cell as the matrix phase and FCC crystal cell as the reinforcement phase,two types of dual phase lattice sandwich structures and single phase lattice sandwich structures with the reinforcement phase parallel to and perpendicular to the loading direction were designed,respectively.Using 316 L stainless steel powder as the raw material,SLM technology was used to prepare the sandwich structures.The structural characteristics of the prepared lattice sandwich structures were studied through SEM experiments;Quasistatic compression experiments were conducted to investigate the mechanical properties,energy absorption capacity,and deformation behavior of lattice sandwich structures.The results show that the two-phase lattice sandwich structure BFZ-A with the reinforcement phase parallel to the loading direction has the greatest improvement in elastic modulus and specific elastic modulus,increasing by 20.23% and 25.7%,respectively;The dual-phase lattice sandwich structure BF-A with the reinforcement phase perpendicular to the loading direction has the greatest improvement in yield strength and specific energy absorption,increasing by 17.31% and 64.29%,respectively;At the same time,the deformation behavior of the two-phase lattice sandwich structures BF-A and BF-B is a layered deformation of different layers at the upper and lower ends,while the deformation behavior of the single-phase lattice sandwich structure BCC is a continuous deformation from the upper and lower ends to the middle.(2)Using BCC crystal cell as the matrix phase and FCC crystal cell as the reinforcement phase,two types of dual phase lattice structures and single phase lattice structures with the reinforcement phase perpendicular to the loading direction were designed.Using Ti6Al4 V titanium alloy powder as the raw material,SLM technology was used to prepare the lattice structure.The structural characteristics of the prepared lattice structure were studied through SEM experiments;Quasistatic compression experiments were conducted to investigate the mechanical properties,energy absorption capacity,and deformation behavior of lattice structures.The results show that the two-phase lattice structure TBF-A with the reinforcement perpendicular to the loading direction has the greatest improvement in elastic modulus,yield strength,and specific absorption energy,with increases of 38.45%,23%,and 150%,respectively;At the same time,the deformation behavior of dual phase lattice structures TBF-A and TBF-B is that different phase layers produce different local fractures,while the deformation behavior of single lattice structure BCC is that of overall shear fracture along 45 °.(3)Using numerical simulation software ABAQUS,the deformation processes of dual phase lattice structures and single phase lattice structures perpendicular to the loading direction were numerically solved,and their deformation behavior and stress distribution during quasi static compression were studied.The results show that the high stress continuous region area of the FCCZ layer in the two-phase lattice sandwich structures BF-A and BF-B is significantly larger than that of the BCCZ layer;The stress of the FCC layer in the dual phase lattice structures TBF-A and TBF-B is mainly concentrated on the face diagonal nodes,while the stress of the BCC layer is mainly concentrated on the body center nodes. |
